1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device with improved reflectivity and transmissivity.
2. Description of the Related Art
For example, partial transmissive-type liquid crystal display devices that have a transmitting section and a reflecting section in one subpixel are used as displays for mobile phones, as described in JP-A-2003-344837.
FIG. 23 is a plan view of an example of a subpixel of a known partial transmissive-type liquid crystal display device. FIG. 24 is a sectional view taken along line A-A′ of FIG. 23. FIG. 25 is a sectional view taken along line B-B′ of FIG. 23. FIG. 26 is a sectional view taken along line C-C′ of FIG. 23.
Referring to FIG. 23, reference numeral 30 denotes a transmitting section and numeral 31 denotes a reflecting section. FIG. 25 shows a cross section of the transmitting section 30. FIG. 26 shows a cross section of the reflecting section 31. The partial transmissive-type liquid crystal display device shown in FIG. 23 is viewed from the main surface of a glass substrate SUB2.
Referring to FIGS. 23 to 26, symbols SUB1 and SUB2 indicate a glass substrate, RET indicates a retarder, GI indicates a gate insulating film, PAS1 to PAS4 indicate an insulating film, POL1 and POL2 indicate a polarizer, BM indicates a black matrix, CFR, CFG, and CFB indicate a color filter, OC indicates a protection layer, MR indicates a recessed layer, AL1 and AL2 indicate an alignment layer, RAL indicates a reflecting electrode, LC indicates a liquid crystal layer, PIX indicates a pixel electrode, COM indicates an counter electrode, GL indicates a scanning line (a gate line), and DL indicates a video line (a drain line or a source line).
The known partial transmissive-type liquid crystal display device shown in FIG. 23 has the pixel electrode PIX and the planar counter electrode COM deposited with an interlayer insulating film PAS2 sandwiched therebetween, in which arch electric flux lines formed between the pixel electrode PIX and the counter electrode COM are distributed in such a manner as to pass through the liquid crystal layer LC to change the orientation of the liquid crystal layer LC.
The pixel electrode PIX is 4 μm in width, and 6 μm in gap width, in which case the density of the lines of electric force and the torque that adjacent lines of electric force apply to the liquid crystal layer LC are maintained in relatively good balance to enable transmission and reflective display.
The length of the cell gap of the reflecting section 31 is set at about half of that of the transmitting section 30. This is for the purpose of substantially matching the optical path lengths of the transmitting section 30 and the reflecting section 31 to each other because light passes through the reflecting section 31 two times to and back.
While the transmitting section 30 shows the brightness of light using the double refraction of the liquid crystal layer LC, the reflecting section 31 shows the brightness using the double refraction of a retarder (½ wave plate) RET and the liquid crystal layer LC disposed in the liquid crystal display panel.
FIG. 27 is a plan view of a TFT substrate side subpixel of an example of a known transmissive liquid crystal display device. FIG. 28 is a plan view of a subpixel in which the TFT substrate shown in FIG. 27 and a CF substrate are placed one on another. FIG. 29 is a sectional view taken along line M-M′ of FIG. 28.
Referring to FIGS. 27 and 29, symbols SUB1 and SUB2 indicate a glass substrate, GI indicates a gate insulating film, PAS1 to PAS4 indicate an insulating film, POL1 and POL2 indicate a polarizer, BM indicates a black matrix, CFR, CFG, and CFB indicate a color filter, OC indicates a protection layer, AL1 and AL2 indicate an alignment layer, LC indicates a liquid crystal layer, PIX indicates a pixel electrode, COM indicates an counter electrode, GL indicates a scanning line (a gate line), DL indicates a video line (a drain line or a source line), and CH indicates a contact hole.
The liquid crystal display device shown in FIG. 27 has a comb pixel electrode PIX and a planar counter electrode COM disposed with the interlayer insulating film PAS2 sandwiched therebetween, in which arch electric flux lines formed between the pixel electrode PIX and the counter electrode COM are distributed in such a manner as to pass through the liquid crystal layer LC to change the orientation of the liquid crystal layer LC.
At that time, the density of the lines of electric force and the torque that adjacent lines of electric force apply to the liquid crystal layer LC are maintained in good balance to enable transmissive display.
Here, as a prior art document relevant to the present invention, a following patent document is named.    [Patent document 1] J-P-A-2003-344837